Answer:
The system that moves blood throughout the body.
Birds have hollow bones due to the fact thay need to be as light as possible for their wings to generate enough lift for them to fly
Option 3; the other grams were realeased as a gas
The correct answer to this question is this one: they lacked oxygen. The earliest organisms were completely heterotrophic in nature because of the reason that they lacked oxygen. <span>A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. </span>
Answer:
it's called transpiration when stomata opens and release extra water
